Production of gasoline hydrocarbons



Feb. 27, 1945. c, F. TEICHMANN ET AL 2,370,507

PRODUCTION OF GASOLINE HYDROCARBONS Filed Aug. 22, 1941 F G I WA TER 14SC BEE R U R 5 E PA R A Tl ON HEAT EXCHGP. HEATER CONVERSION 2 3 4.WAVAVAVAVAVRVAVIL 1 V V Y V V V X I [I] OUTLE T WE LL [I2 FRACT/ONA TORv 4 AND/OR c5 TANK ETC.

2 HIGHER BOILING FR A c r/o/v SEPARATION SEPARATION I22 CATALYTIC HEATERCONVERSION g qu/sursa 45 f24 /25 c FRACTION c HEAVIER v TANK TANK 30 .CATALYT/C CON VERSION CONVER TED HYDROCARBONS CHARLES F. TEICHMANN ARTHURR. GOLDSBY GoRoo/v A. KESSLER MAX NEl/HAus THE! .4 TTORNE 145' PatentedFeb. 27, 19 45 PRODUCTION OF GASOLINE HYDROCARBON S Charles F.Teichmann, Mount Vernon, and Arthur B. Goldsby, Beacon, N. Y., Gordon A.Kessler, Ridgewood, N. J and Max Neuhaus, Bronxville, N. Y., assignor's,by mesne assignments, to The Texas Company, New York, N. Y. acorporation of Delaware Application August 22 7 Claims.

This invention relates to production of valuablegasoline hydrocarbonsfrom subterranean distillate reservoirs and particularly to thetreatment of low boiling gasoline hydrocarbon constituents of the'distillate obtained from such reservoirs.

In its broadest aspect the invention contemplates subjectingthedistillate fluid obtained from a distillate reservoir, or suitablefractions of such fluid, to conversion so as to produce gasolinehydrocarbons of improved antiknock value from the distillate. Theconverted hydrocarbons are removed and the residual gaseous hydrocarbonconstituents of the well fluid, including, if desired, gaseousconstituents produced in the conversion treatment, are returned underelevated pressure to the subterranean distillate reservoir.

, 1941, Serial No. 407,984

lication, for every binary or other mixture of normally gaseoushydrocarbons, there is a boundary on the pressure-temperature planewithin Advantageously the conversionis effected under pressure which isnot substantially different from that at which the distillate -fluidis'obtained from the well.

The fluid from subterranean distillate reservoirs is composed mainly ofnormally gaseous in the subterranean formation. Reduction in theformation pressure is usually accompanied by substantial condensation ofliqueflable hydrocarhens in the reservoir itself thereby resulting inthe permanentloss of useful hydrocarbons. For this reason it isdesirable to avoid reduction in the formation pressure.

This condensation which occurs upon reduction vof the pressure is knownas retrograde condensation. Retrograde condensation, as described in thearticleby George G, Brown entitled Retrograde condensation and thecritical phenomena". published inthe Proceedings of the 18th AnnualConvention of the Natural Gasoline Association of America, held May 3-5,1939, is

that condensation Which-is brought about by reduction. in pressure eventhough the temperature remaiiis constant. As de scribed in this pub-Therefore, if the temperature and pressure of a mixture of hydrocarbonswhich is already under conditions of temperature and pressuresubstantially above the critical point, are reduced through th two-phaseboundary, retrograde condensation occurs as described in the foregoingpublication.

Consequently, it is desirable to return the residual gases, afterrecovery of the gasoline hydrocarbons, to the reservoir or subterraneanformation under elevated pressure so as to maintain the formationpressure and thereby avoid the 'foreg'oing'condensation of liquefiablehydrocarbons within the formation.

Preferably in accordance with the present invention the well fluid istreated without substantial reduction in pressure so as to convertgaso-.

line hydrocarbons such as normal butane and normal pentane, etc., togasoline hydrocarbons of improved antiknock value. The convertedhydrocarbons are separated from the treated fluid without substantialreduction in pressure and the residual gases then returned to theformation.

The conversion treatment may involve thermal or catalytic reforming attemperatures of about 700 to 1100 F; One advantageous form oftreatmentcomprises hydroforming by contact with a hydroforming catalyst such as amixture of aluminum and molybdenum oxides or aluminum and chromiumoxides at a temperature inthe range about 800 to 1000 F. Still anotherform of treatment comprises isomerization by contact with anisomerization catalyst such as an active metallic halide .at atemperature of about 200'to 400 F.

The recovered hydrocarbons includingmainly converted hydrocarbons are ofimproved antialkylation reaction for'reaction with -.lowboiL ing olefinhydrocarbons to produce normally liqvalue. Isopentane may be separatelyreacted with hydrocarbon polymers such as (11- and triisobutylenes bycontact with a suitable alkylation catalyst for the production of safetyfuel of high antiknock value.

The temperatures of distillate fluids at the well head are usually ofthe order of about 100 to 175 F. while the pressures are of the order ofabout 1000 to 5000 and usually of about 2000 to 3500 pounds per squareinch gauge.

In order to efiect the desired conversion it is conditions which arenear to or outside the twophase boundary for the well fluids so that thefluid is substantially entirely in a single homogeneous phase. Theconversion reaction may be carried out under temperature and pressureconditons which are somewhat above the critical point for the reactinghydrocarbons, for example, above the critical point for butane andlighter hydrocarbons, so that the pressure upon the hydrocarbon reactionmixture may be subsequently reduced through or within the retrogradecondensation range oi liqueflable hydrocarbon constituents of themixture such that substantial condensation occurs. The resultingcondensate comprising converted hydrocarbons is separated and theresidual gases are thereafter forced hacl: into. the subterraneanformation.

By effecting the conversion treatment of the hydrocarbons withoutsubstantial reduction in the pressure or in other words, at about thepressure corresponding to the pressure of the fluid as obtained from.the well, the reed hydrocarbons undergoing treatment are thus in a densephase during the reaction. This favors more efiective contact betweenthe hydrocarbons undergoing conversion and the catalyst. 'It alsopermits a higher throughput with a short time of contact.

The well fluid consists mainly of gaseous hy drocarbons, particularlymethane. Normal butane ma amount to about 1 or 2 moi per cent of thefluid so that the proportion of gaseous material such as methane isrelatively large as compared to the content of butane and highermolecular weight hydrocarbons.

The presence of relatively inert gaseous material such as methane inrelatively large proportion to the hydrocarbons undergoing conversion isadvantageous from the standpoint of inhibiting undesired side reactionsand catalyst deterio- 2,370,507 uid gasoline hydrocarbons of highantiknock mal butane and normal pentane. Removal of the hexane andheavier may be efiected by selective absorption, adsorption or byretrograde condensation, and these higher molecular weight hydrocarbonsmay be subjected to separate conversion treatment or separately disposedof as desired.

In order to describe the invention more fully reference will now be madeto the figures of the accompanying drawing.

Referring to Fig. 1, well fluid is obtained from an outlet well Itapping a subterranean distillate reservoir.

The fluid is obtained under a pressure, for example, of about 2000pounds and at a temperature of about 125 F. This fluid ma have thefollowing approximate composition:

- I Moi per cent Methane 89.46

Where the fluid is subjected to an isomerization reaction by contactwith a catalyst comprising aluminum chloride and hydrogen halide, thewell fluid without substantial reduction in pressure is passed through aheat exchanger 2 and heater 3 wherein it is raised to a mmperature ofabout 200 to 250 F. The so heated fluid is then conducted to anisomerization plant 3 wherein the normal paramn constituents such asnormal butane and normal pentane are converted to isoparaflins.

The fluid containing converted hydrocarbons is advantageously passedthrough pipe ii to the previously mentioned exchanger 2 wherein it flowsin indirect heat exchange relationship with the entering ieeol.Thereafter it is conducted to a hydrocarbon recovery plant '5 wherein thbutanes and higher molecular weight hydrocarbons including convertedhydrocarbons are separated from the residual gases. This separation maybe eflected by absorption in a suitable absorption oil, by adsorptionduring contact with a solid adsorptive material or by retrogradecondensation.

Where the operation is efiected by absorption the fluid leaving thecatalytic treating plant it is cooledto a temperature of about to F. andthe cooled fluid subjected to contact. with heavy oil, gas oil or othersuitable absorption menstruum. The absorption may be carried out eitherby concurrent or countercurrent contact between the well fluid and theabsorption oil, without substantial reduction in pressure and underconditions of temperature and proportion of absorption oil to fluid suchthat normal butone and higher molecular weight hydrocarbons areselectively absorbed from the residual gases.

Where the separation is effected by adsorption the catalytically treatedfluid without substantial reduction in pressure and advantageously afterhaving been cooled to a temperature of about 90 to 100 F. is conductedthrough a tower packed with a solid adsorptive material such as charcoalor silica gel under conditions such that a normal butane and highermolecular weight hydrocarbons are selectively adsorbed in the adsorbentmaterial.

The adsorption operation is advantageously ef-,

fected in a plant having a plurality of adsorption towers so that whileone adsorption'tower is onstream anothertower is oifstreamfor-regeneration during which the adsorbed hydrocarbons are strippedfrom the adsorbent material inthe conventional manner.

' Where the separation is efiected by retrograde condensation this maybe accomplished by passing the catalytically-treated fluid to a closedvessel wherein the pressure is-reduced through or motor fuel stock orfor further fractionation to segregate the isoparamns therefrom forfurther reaction with olefins to form alkylated hydrocar bons. I

- The recovered hydrocarbons from the tank ll may be passed to afractionator l2 for the purpose of segregating hydrocarbons or fractionstherefrom. Th recovered hydrocarbons ,accumulating in the tank It maycontain substantial amounts of gaseous material which will be releasedupon reduction of pressure. Accordingly,

in the fractionator I! the overhead fraction may The gaseous fractionremoved as an overhead from the fractionator i2 is advantageously in-'jected by means of a compressor into the untreated well fluid passing tothe catalytic conversion plant 4 and in this way the gaseoushydrocarbons may be ultimately returned to the reservoir while at'thesame time taking advantage of the promotional effectof the retainedhydrogen chloride during the catalytic reaction.

On the other hand, the gaseous fraction may be injected directly to theeflluent'fluid passing through the pipe 9 for return to the input well.The hydrogen chloride present in the returning residual gases thusserves, upon return to the input well, to open up the formation.

If desired to avoid or substantially reduce'the amount of hydrogenchloride passing to the inletwell, the thermally orcatalytically treatedwell' fluid may be subjected to scrubbing withwater.

, Thus, the treated mixture flowing through the previously mentionedseparator The water containing'absorbed hydrogen chloride-is withdrawnfrom the absorber and may be disposedof in anysuitable manner or may beconcentrated in order to recover. the acid.

The scrubbing or washing step may be applied following the separationtreatment in the separator I. In other words, the residual gases flowingthrough the pipe 9 may be subjected to the scrubbing or washingtreatment to remove hydrogen chloride.

If instead of subjecting the liquefiable hydrocarbons of the well fluidto the isomerization they are subjected to hydroforming, the methodofflow is generally similar to that already described above in connectionwith Fig. 1 with the exception that the water. washing or scrubbing. ofthe treated hydrocarbon mixture is omitted. Thus,

the well fluid from the outlet well I is passed through the heatexchanger and the heater so as to heat it to a temperature in the rangeof about 850 to1050 F. The heated mixture is then passed to theconversion zone 4 wherein it .is subjected to contact with a suitablehydroforming catalyst, as, for example, a mixture of aluminum andmolybdenum oxides.

Since the feed mixture contains a relatively large proportion of methanethere is thus present in the reaction a large amount ofhydrogen-comtaining gas. Provision may be made for recycling hydrogenand hydrogen-containing gases produced in the reaction.

It is contemplated that the .well fluid prior to introduction to thecatalytic conversion unit t may be subjected to chemical treatment suchas scrubbing with caustic or other alkali solution for the purpose ofremoving sulfur compounds and other impurities which if not removedwould cause catalyst deterioration in the subsequent catalyticconversion operation.

Referring now to Fig. 2 the well fluid from the outlet well 20 which maybe similar to that discharged from outlet well I of Fig. 1 and may alsobe under similar conditions of temperature and pressure, is conductedthrough a pipe 2! to a separation plant 22 wherein the fluid isseparated into fractions, one fraction consisting, for example, ofbutane and lighter hydrocarbons; and the. other fraction consisting ofhydrocarbons heavier than butane, namely, pentane and hexane, etc.

This separation may be eiTected by absorption in a suitable absorptionliquid or adsorption by contact with a suitable solid adsorptivematerial.

The absorption or adsorption operations may be carried out in theconventional manner such as described in connection with similaroperations in the recovery plant I of Fig. 1. In any case the separationinto 04 and lighter and Cs and heavier fractions is efiected withoutsubstantialreduction in pressure. If desired the pressure on the wellfluidmaybe increased so that the separation may existing at the outletof well 20.

The C4 and lighter fraction consisting mainly of methane is passedthrough a heater or heat exchange apparatus 23 wherein it is raised tothe requisite temperature for efiecting the subsequentcatalytic-conversion, in this case isomerization.

The heated fluid is then passed through a cata- 'lytic conversion unit24, wherein the 'normal butane is subjected .to contact with anisomeriza tion catalyst maintained underisomeriz-fng conditions, butwithout substantial reduction in pressure of the well fluid;

The catalytically treated fluid is then passed to a separation orrecovery unit 2i similar to the recovery unit I of Fig. 1, and by whichmeans C4 and heavier hydrocarbons are separated and recovered from theresidual gases. The residual gases are thereafter forced by means of apump or compressor 26 into an input well 21 for return to thesubterranean formation.

The recovered C4 and heavier fraction is passed to a storage tank 28.The recovered fraction may be disposed of as described in connectionwith the liquid accumulating in tank II in Fig. 1.

The C and heavier fraction removed from the separation unit 22 is passedto a storage tank 29 and may be disposed of as blending stock forgasoline. Advantageously, however, it is subjected to a catalyticconversion treatment such as previously disclosed. In such case thefraction is conducted from the tank 29 to a separate conversion unit 30wherein it is subjected to the conversion treatment.

The resulting converted hydrocarbons rich in isoparaffins can then beused as a blending stock or can be fractionated to segregate individualhydrocarbons or hydrocarbon fractions therefrom for such furtherdisposition as may be desired.

While reforming and isomerization have been mentioned in connection withthe catalytic conversion of readily liquefiable hydrocarbons of the Wellfluid, nevertheless it is contemplated that the conversion treatment maycomprise other desired types of conversion reactions either catalytic orpyrolytic such as cracking and dehydrogenation, for example, in order toobtain the desired type of converted hydrocarbon products. More elevatedtemperatures are usually required Where a cracking type of operation isemployed, and the catalysts used may be aluminum silicates, natural orartificial, or silicate or other solid adsorptive materials impregnatedwith metals and metal compounds.

Where a simple isomerization reaction is involved the catalyst isadvantageously one selected from the group of metallic halides such asaluminum chloride, iron chloride, zirconium chloride, metallic mixedhalides such as aluminum chlorofluoride (AlClFz), aluminumfiuorochloride (AlFClz) and the like,.promoted with a hydrogen halidesuch as hydrogen chloride.

Under certain conditions a promoter may not be required, for example, inthe isomerization of pentane and the like with a metallic mixed halidecatalyst.

The isomerization of the normally liquid fraction accumulating in thetank 29 of Fig. 2 is ad- ---'cyclohexane, etc., for the purpose ofinhibiting cracking of hydrocarbons and deterioration of the catalyst.For example a portion of the residual gases from the reaction inconversion zone 24 may be mixed with the hydrocarbon feed to theisomerization reaction in conversion zone 30.

Provision may be made for recycling hydrogen and hydrogen-containinggases, formed in the conversion, through the conversion reaction zone asdescribed in connection with Fig. 1. Moreover the conversion in unit 30may be carried out underpressure corresponding substantially to that ofthe well fluid at the head of the outlet well.

Provision may be made for altering the pressure prevailing at any stagein the process. For example, in the absorption or adsorption operationsthe pressure may be adjusted, depending upon temperature and otherconditions, in order to obtain the desired separation. If it isnecessary to reduce the pressure, then provision must be made forincreasing the pressure in a, later stage or stages of the processinorder to force the residual gases back into the inlet well.Advantageously a substantial reduction in overall pressure is avoided soas to reduce the amount of compression required in order to return theresidual gases to the subterranean reservoir.

While return of residual gases to the same reservoir has been described,it is contemplated that they may be returned, all or in part, to adifferent or neighboring subterranean reservoir for the purpose ofmaintaining or aiding in maintaining reservoir pressure.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

We claim:

1. A process of producing low boiling gasoline hydrocarbons of improvedantiknock value from the well fluid of a subterranean distillatereservoir which comprises obtaining well fluid from an outlet well ofthe reservoir at a high well head pressure, said fluid containinggaseous hydrocarbons having 4 carbon atoms and less per molecule andhigher molecular weight hydrocarbons having 5 and more carbon atoms permolecule, removing said higher molecular weight hydrocarbons from saidfluid without substantial reduction in pressure, and then subjecting theresidual fluid while at substantially well head pressure to contact withan isomerization catalyst in the presence of hydrogen halide at anelevated temperature in the range below about 400 F. such thatsubstantial isomerization of normal paraffin constituents of theresidual fluid to isoparafilns occurs, thereafter separating from saidresidual fluid containing isomerized hydrocarbons and hydrogen halide atpressures within the retrograde condensation range a hydrocarboncondensate, removing the resulting condensate from residual gas andrecycling residual gas containing hydrogen halide to'an inlet well ofsaid reservoir.

2. A process of producing low boiling gasoline hydrocarbons of improvedantiknock value from the well fluid of a subterranean distillatereservoir whichv comprises obtaining well fluid from an outlet well ofthe reservoir at a. high well head pressure said fluid containinggaseous hydrocarbons having less than 4 carbon atoms per molecule andhigher molecular weight hydrocarbons having 4 and more carbon atoms permolecule, separating from said fluid without substantial reduction inpressure a fraction comprising C4 hydrocarbons and lighter constituentsof the fluid,

' subjecting said C4 and lighter fraction while under substantially wellhead pressure to contact with an isomerization catalyst maintained inthe presence of hydrogen halide at an elevated temperature in the rangebelow about 400 F. such that substantial isomerization of normal butaneto isobutane occurs, passing the isomerized fraction containing somehydrogen halide to a separating zone, effecting separation therein ,of ahydrocarbon condensate without substantial reductlon in pressure,removing the resulting condensate from residual gas and recyclingresidual gas containing hydrogen halide to an inlet well of saidreservoir.

3. A process of producing low boiling gasoline hydrocarbons of improvedantiknock value from the well fluid of a subterranean distillatereservoir which comprises obtaining well fluid from an outlet well ofthe reservoir at a high well head pressure, said fluid containinggaseous hydrocarbons having less than 4 carbon atoms per molecule andhigher molecular weight hydrocarbons having 4 and more carbon atoms permolecule, separating said fluid without substantial reduction inpressure into a fraction comprising C4 hydrocarbon and lighterconstituents of the fluid and a fraction comprising higher molecularweight hydrocarbons, subjecting said C4 and lighter fraction while undersubstantially well head pressure to contact with an isomerizationcatalyst maintained in the presence of hydrogen halide at an elevatedtemperature in the range below about 400 F. such that substantialisomerization of normal butane to isobutane occurs, passing theisomerized fraction containing some hydrogen halide to a separatingzone, effecting separation therein of a hydrocarbon condensate withoutsubstantial reduction in pressure, removing the resulting condensatefrom 'the residual gas, separately subjecting said higher molecularweight fractionto an elevated temperature in the range 700 to 1100 F.whereby said hydrocarbons undergo conversion into hydrocarbons ofimproved character for gasoline manufacture and some gas, removing thegasoline hydrocarbons from the products of said conversion and recyclingthe residual gas containing hydrogen halide from the isomerizationreaction and the conversion reaction to an inlet well of said reservoir.

4. A process for recovering hydrocarbons from high pressure well fluidwhich comprises obtain ing well fluid from an outlet well of a subterranean formation, said fluid containing gaseous hydrocarbons having 4carbon atoms and less per molecule and some higher molecular weighthydrocarbons, removing said higher molecular weight hydrocarbons fromthe residuaLfiuid, subjecting the residualfluid to contact with an flns,which comprises flowing said fluid from an outlet well of a subterraneanformation, subjecting normally gaseous and liquefiable hydrocarbonconstituents of said fluid to contact with an isomerization catalyst inthe presence of hydrogen halide at an elevated temperature such thatsubstantial isomerization of normal parafiin hydrocarbons occurs,passing resulting catalytically treated hydrocarbons containing somehydrogen halide to a separation zone, effecting separation therein of ahydrocarbon condensate, removing said condensate from residual gascontaining hydrogen halide, and recycling said residual gas containinghydrogen halide to an inlet well of said formation.

6. A' process for recovering hydrocarbons from high pressure well fluidcontaininggaseous and liquefiable hydrocarbons includin normalparafflns, which comprises flowing said fluid from an outlet well'of asubterranean formation, subjecting normally gaseous and liqueflablehydrocarbon constituents of said fluid to contact with a metallic halidecatalyst in the presence of hydrogen halide at an elevated temperaturenot exceeding about 400 F., passing resulting catalytlcally treatedhydrocarbons containing some hydrogen halide to a separation zone,effecting separation therein of a hydrocarbon condensate, removing saidcondensate from residual gas containing hydrogen halide, and recyclingsaid residual gas containing hydrogen halide to' an inlet well of I saidformation.

7. A process for recovering hydrocarbons from high pressure well fluidcontaining gaseous and liqueflable hydrocarbons including normalparaffins which comprises flowing said well fluid from an outletwell ofa subterranean formation, subjecting normally gaseous and liqueflablehydrocarbon constituents of said fluid to contact with an isomerizationcatalyst in the presence of hydrogen halide at an elevated temperaturesuch that substantial isomerization 0! normal paraflins occurs, passingresulting catalytically treated hydrocarbons containing hydrogen halideto a sepisomerization catalyst in the presence of hydrogen halide at anelevated temperature not exceeding about 400 F., such that substantialisomerization of C4 hydrocarbon occurs, passing the catalyticallytreated fluid containing some hydrogen halide to a. separating zone,effecting separation therein of a hydrocarbon condensate, re-

moving said condensate from the residual gas containing hydrogen halide,and recycling said residual gas containing hydrogen halide to an inletwell of said formation.

5. A processior recovering hydrocarbons mm high pressure well fluidcontaining Sasecus and limieflable hydrocarbons including normal para!-arating zone, effecting separation therein from residual gas of ahydrocarbon condensate containing some normally gaseous constituentsincluding hydrogen halide, removing said condensate from residual gas,subjecting the removed condensate to fractionation into a normallygaseous fraction containing some hydrogen halide and a higher boilingtraction, removing the higher boiling fraction and recycling residualgas and said normally gaseous fraction containing hydrogen halide to aninlet well of said formation.

- CHARLES F. 'IEICHMANN.

ARTHUR R. GOLDSBY. GORDON A. KESSLER. MAX NEUHIiUS.

